The present invention relates to a method of hot rolling rods such as iron rods and iron alloy rods.
Cemented carbides and die steel have been used as hot rolling tools for iron and iron alloy rods.
However, the production conditions of mass produced articles represented by wire drawing rolls and the like have become severer year after year due to demand for higher precision and greater economical efficiency. Also, for plastic deformation tools, the demand is increasing for improved resistance to heat, wear, thermal shock and the like.
In order to meet the demand, new materials are being developed one after another in the field of cemented carbide, die steel, high-speed steel and the like. However, new materials having the aforesaid characteristics have not yet been found.
As described hereinbefore, the materials of hot rolling tools generally comprised steels such as tool steel and cemented carbide. There has been very little progress in the development of new materials for hot rolling tools.
On the contrary, since its characteristics such as shock resistance, thermal shock resistance and brittleness are inferior to those of the aforesaid materials, ceramics are beginning to be used only in the field of guide rolls and the like subjected to relatively small stress. Thus, the idea of employing ceramics as materials of rolling rolls has scarcely been conceived heretofore.
That is to say, although rolling rolls as hot rolling tools are disclosed in Japanese Patent Laid-Open No. 53-78216 (1978), the conditions under which they are employed and the effects obtained thereby are not disclosed at all.